• Korean Journal of Mathematics
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• 제16권3호
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• pp.335-348
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• 2008

We define Fourier-Yeh-Feynman transform and convolution product on the Yeh-Wiener space, and establish the existence of Fourier-Yeh-Feynman transform and convolution product for functionals in a Banach algebra $\mathcal{S}(Q)$. Also we obtain Parseval's relation for those functionals.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.253-256
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• 2000

In this paper, we propose the lossless image compression algorithm using the integer wavelet transform. Recently, the S＋P transform is widely used and computed with only integer addition and bit-shift operations, but not proper to remove the correlation of smooth images. then we compare the Harr wavelet of the S＋P transform with various integer coefficient filter banks and apply 9/7 ICFB to the wavelet transform. In addition, we propose a entropy-coding method that exploits the multiresolution structure and the feedback of the prediction error, and can efficiently compress the transformed image for progressive transmission. Simulation results are compared to the compression ratio using the S+P transform with different types of images.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.616-624
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• 2015

Flashover of power transmission line insulators due to contamination is a major threat to the reliable operation of power system. This paper deals with the analysis of leakage current characteristics of polymeric insulator using S-Transform technique in order to develop a better diagnostic tool to identify the surface condition of outdoor polymeric insulators. In this work, experiments were carried out on 11 kV silicone rubber insulator under AC voltage at different pollution levels. Moving average technique was adopted to find the trend followed by LC peak at different relative humidity conditions. S-Transform was used to find the relationship between energy and frequency content of the leakage current signal with respect to increase in pollution level over a period of time. From the S-Transform time-frequency contour analysis, point of transition to severe arcing due to increase in pollution and its thershold limit were evaluated. Reported results show that the surface condition of insulators could be easily identified from the S-Transform time-frequency analysis of leakage current signals.

• 대한수학회논문집
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• 제19권1호
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• pp.93-111
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• 2004

In this paper, we use a generalized Brownian motion process to define a generalized Feynman integral and a generalized Fourier-Feynman transform. We also define the concepts of the multiple Lp analytic generalized Fourier-Feynman transform and the generalized convolution product of functional on function space $C_{a,\;b}[0,\;T]$. We then verify the existence of the multiple $L_{p}$ analytic generalized Fourier-Feynman transform for functional on function space that belong to a Banach algebra $S({L_{a,\;b}}^{2}[0, T])$. Finally we establish some relationships between the multiple $L_{p}$ analytic generalized Fourier-Feynman transform and the generalized convolution product for functionals in $S({L_{a,\;b}}^{2}[0, T])$.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.900-903
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• 2002

This paper proposes the use of wavelet packet transform in a transform based video coding scheme, which is mainly used in low/very low bit-rate video coding schemes i.e. H.263 standard. In the experiments, the discrete cosine transform in the video coding scheme is replaced by the wavelet packet transform, and the improved performance in term of peak signal to noise ratio is measured and compared with the results obtained from the coding scheme implementing the ordinary wavelet transform. The experimental results show an impressive improvement obtained from the use of wavelet packet transform.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.269-273
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• 2000

This paper describes Active Noise Control (ANC) using Discrete Wavelet Transform (DWT) Domain Least Mean Square (LMS) Method. DWT-LMS is one of the transform domain input decorrelation LMS and improves the convergence speed of adaptive filter especially when the input signal is highly correlated. Conventional transform domain LMS's use Discrete Cosine Transform (DCT) because it offers linear band signal decomposition and fast transform algorithm. Wavelet transform can project the input signal into the several octave band subspace and offers more efficient sliding fast transform algorithm. In this paper, we propose Wavelet transform domain LMS algorithm and shows its performance is similar to DCT LMS in some cases using ANC simulation.

• 대한수학회지
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• 제39권5호
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• pp.709-729
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• 2002

Using the well known Hermite-Hadamard integral inequality for convex functions, some inequalities for the finite Hilbert transform of functions whose first derivatives are convex are established. Some numerical experiments are performed as well.

• 대한수학회보
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• 제39권4호
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• pp.543-559
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• 2002

Some inequalities and approximations for the finite filbert transform by the use of Ostrowski type inequalities for absolutely continuous functions are given.

• 한국전자파학회논문지
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• 제19권9호
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• pp.968-977
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• 2008

본 논문에서는 Fourier-transform analysis와 Wiener-Hopf technique을 사용하여 병렬 슬릿에 의한 TE파 산란의 완전한 표현식을 유도하고 두 방법의 특징을 비교하고자 한다. Fourier transform analysis는 슬릿의 폭이 좁은 경우에는 빠른 수렴해를 얻을 수 있으며, Wiener-Hopf technique은 슬릿의 폭이 넓을 경우(상호 유도 결합이 적은 경우)에 매우 정확한 근사식 결과를 나타내며, 위의 두 해석 결과는 비교적 일치하는 결과들을 보여준다.

• 한국인터넷방송통신학회논문지
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• 제12권5호
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• pp.205-211
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• 2012

본 논문에서는 웨이블릿 변환과 Haar 변환을 기반으로 적응적 문턱치와 가중치를 이용하여 의료영상의 화질을 개선하는 알고리즘을 제안한다. 첫째, 화질이 저하된 의료영상에 대해 웨이블릿 변환을 수행하고 분해된 고주파 밴드에 대해 Haar 변환을 수행한다. 둘째, 고주파 각 밴드에 대해 적응적 문턱치를 이용하여 잡음을 제거한다. 셋째, 잡음이 제거된 고주파 밴드에 대해 적응적인 가중치를 이용하여 계수를 향상한 후, Haar 역변환 및 웨이블릿 역변환을 수행하여 복원영상을 얻는다. 마지막 단계에서는 복원된 영상의 화소 값의 범위가 좁아졌으므로 비선형 히스토그램 평활을 이용하여 화소 값의 범위를 조절하고 명암 대비가 좋은 향상된 영상을 얻는다.